DE19926414A1 - Combination lens preparation tool has a cutting ring and a polishing core on a common shaft with the core axially adjustable by means of a pressure membrane - Google Patents

Abstract

The tool rotates on a hollow shaft (3) and a cutting ring (8) forms the surface of a revolving lens after which air pressure through the shaft presses the elastic membrane (19) against the polishing core (12) to enable the polishing pads (18) to contact the lens surface.

Description

The combination tool for processing optical lenses is a Device according to the preamble of main claim 1. To linguistic simplification chung is the subject of the invention only as a combination tool designated. The aim of the present invention is to grind and polish To design lenses more cost-effectively while maintaining the quality of the ones produced Improve lens surfaces in terms of roughness and shape accuracy. These tasks are solved with the features of claim 1.

According to the invention there are two processing tools in the combination tool arranged coaxially to each other, which are used successively on the same lens come. On the one hand, it is a pot tool with a ring cutter and on the other hand a molding tool, the surface of which is different Abrasive pellets or polishing foils can be occupied, and with regard to its integration in the combination tool has some important features according to the invention.

The combination tool is provided as a grinding tool or as a polishing tool insert tool. It is also possible to combine these two work gears, for example by first grinding with the potting tool while is then polished with the molding tool.  

In any case, the two tools mentioned are used one after the other. Working with the combination tool is particularly cost-effective since two Operations can be carried out with a single tool. Also the required machine is inexpensive because it only has one workpiece and one Tool spindle required. By using a molding tool that in the Combination tool is integrated, there are also labor costs Savings since the cutting performance of the mold as a result of its flat contact with the lens is significantly higher than when using a Pot tool is the case.

A special feature of the invention is that the molding tool with respect its axis inclination is freely movable in an outer housing and on a flexible membrane made of elastic material, e.g. B. made of rubber supports. As a result, the molding tool can precisely adapt to the Contour the pre-ground lens. Decisive for the shape accuracy of the Lens is thus the very precise mold to be produced. The fiction moderate combination tool allows, among other things, the advantages of the known Ball pen method to use with mold without the disadvantages in Purchase must be made. It can be essential with the combination tool better shape accuracy and surface roughness are generated than was previously the case with the usual technology was possible.

The combination tool shows in comparison to tools with ball pin that the Corresponding to the state of the art, in addition one not previously known Advantage, which is that the mold is actively driven what Allows corrections to the lens geometry. The combination tool and its with it For this purpose, a non-rotatably connected molding tool is connected to a driven one Tool spindle attached that works in the same direction as the opposite work tool spindle with the lens holder and the lens rotates.  

This gives rise to the aforementioned possibility of specifically influencing the geometry of the generated lens surface in the fine area. For this, the The speeds of the two spindles changed in relation to each other, whereby depending on the radius, on different ring surfaces of the Different relative speeds between the lens surface Form tool and the lens result. These different Relative speeds result in different material removal. This one Effect can be used to make the corrections mentioned with the molding tool to attach the lens shape in the fine area.

This is not possible with the conventional ball pen method, because this If the tool only turns freely due to the friction on the lens. The result The speed cannot be influenced. In addition, the usual Ku gel pen process but also a number of other disadvantages. Such disadvantages are also given in the other methods for lens production.

According to the prior art, the optically active surfaces of lenses through several grinding processes (e.g. coarse and fine grinding) and adhere to them closing polishing processes. For grinding are usually Pot tools used, the diamond-cut ring blades with various grain sizes. These tools can be used in particular spherical make lenses. For this purpose, the pot tool on the tool spindle is one Grinding machine attached, which usually has a CNC control. The The lens blank is placed in a lens holder on a second spindle (Workpiece spindle) of the machine is fixed, opposite the tool spindle stands. At least one of the two mentioned spindles can be tilted (pivoted) so that the pot tool at a predetermined angle meets the lens blank. The geometrical axis of the pot tool goes here through the center of radius of the lens surface to be generated. The pan angle thus determines the radius of curvature of the lens surface created.  

When working with pot tools, there are some major disadvantages as follows:

• - The accuracy of shape generated depends to a large extent on the accuracy the grinding machine used and its control. It can therefore be only produce accuracies of 1 to 2 µ with pot tools.
• - The machine spindles with the pot tools lead at higher speeds to vibrations. These higher speeds are necessary to achieve the required Cutting speeds from 20 to 40 m / sec. to create. Vibrations we always have a negative impact on the work result.
• - There are procedural problems due to imbalance and the bearing play of the machine, which leads to a restless run. This can lead to deep cracking lead in fine grinding, which requires up to 100% longer polishing times can make. This increased polishing effort is then necessary so that Lens surface is processed accordingly.
• - Another disadvantage is that pot tools with the lenses to be processed only one Have line contact. The result is that the material removal per tool rotation is accordingly only slight. To remedy this, use high speeds or cutting speeds worked, leading to the aforementioned problems leads.

To remedy the disadvantages mentioned when working with potting tools the grinding machines became more and more expensive and therefore more expensive pierced. So today the grinding machines are using very expensive techniques such as air bearings and equipped with highly precise control and guidance systems. With the same goal, its supporting structure is greatly oversized, which in particular Counteract vibrations.  

As mentioned, there are several grinding and polishing processes for producing a lens necessary, you have the appropriate grinding and polishing machines in the Equipped with additional spindles during their further development. The goal was here in making lens grinding cheaper while increasing it of quality. A typical example of this are grinding machines with a bottom workpiece spindle and two overhead tool spindles. This can using two pot tools and without having to reclamp the lens, the Coarse and fine grinding can be carried out in succession. Resulting from this time savings and quality improvements since the lens between the two Machining steps do not have to be reclamped. Similar advantages arise if polishing machines are equipped with more than two spindles.

The disadvantage of this further development of grinding and polishing machine technology; that the operation of the machines becomes more and more complicated and the machines themselves, due to the complex equipment, become very expensive. The increased with it Investment, repair and downtime costs reduce the rationalization effects quite considerably.

When using the combination tool according to the invention with two different ones Tools on a simple machine result in better rationalization effects than with the multi-spindle, expensive processing machines. Since the comm biwerkzeug also via a quasi "cardan-mounted", driven molding tool higher quality lenses with shorter processing times generate than this is with pot tools.

The prior art also describes other methods for processing spherical lenses used. This includes the aforementioned ball pen method, at a larger mold from a ball pin against the smaller lens is pressed. The active surface of the mold is a negative one "Imprint" of the lens geometry to be produced.  

In this case, too, the axis of the lens and the axis during machining Axis of the tool inclined to each other.

The use of a shaping tool is advantageous in the ball-pin method, that allows very precise shape accuracy of the lens produced. Because the molding tool can be pressed against the lens by means of the ball pin and align the lens exactly with each other without any tilting. The same effect arises when, conversely, the lens holder with the lens by means of the ball pin ge is pressed against the mold. Fine grinding or polishing The ball pen method is therefore carried out without unwanted constraint between the involved surfaces. When working with the ball pin, the radius center lies point of the ball, the workpiece and the mold on a common Axis.

The ball pin combines the following functions:

• - "Cardanic" compensation of axis inaccuracies between the mold and lens
• - Force transmission into the mold to generate the required working pressure
• - Fixing the position of the mold relative to the lens
• - Storage of the mold (freewheel) to accommodate the friction-related right latin rotary motion

Despite its good properties, the traditional ball pen method has some essential disadvantages that have led to the fact that it is today in its original Chen form is no longer used. The main cause of the disadvantages of the bullet pen method is the concentration of the above four functions on two re relatively small components, namely the ball with its pan.  

The disadvantages of the traditional ball pen method are as follows:

• - With the ball pen either the lens holder with the lens or the Mold are performed. So that the resulting reaction forces between The spherical pin always only makes the lens and the mold too big the corresponding concave component (mold or lens) is held. The The size of these reaction forces depends on the geometric conditions together. The limitation of the possible uses of the ball pin on the ever Weil's concave component is a significant disadvantage because, for. B. when editing concave / convex shaped lenses, the mold and the lens holder the ball pin must be exchanged. It also results from this Tool size restrictions relative to the workpiece.
• - Working with the ball pen method is because of the emerging Reaction forces only possible at low speeds. It follows that only Ma machines with conventional technology can be used, as CNC machines are designed for much higher speeds.
• - The introduction of force to generate the required working pressure using the Ku gel pen is not sensitive enough. This is related to the large, moveable masses with which the ball pin is connected. One of those masses is z. B. the air cylinder, which moves the ball pin axially and said Working pressure generated. In addition, the air cylinder is because of its sealing elements with friction. This leads because of the differences between the Stiction and sliding friction to jerky movements with the ball pin transferred and do not allow sensitive work.
• - On the ball and the corresponding pan there is a high degree of wear due to the frictional relative rotary movement between the lens with the lens holder and the mold.
  The ball and the pan form a slide bearing with a very high surface pressure, which is operated in an abrasive environment, since the cooling liquid and also the polishing suspension contain particles of relatively great hardness.
• - When working with ball pins, the machines cannot be loaded automatically because the ball and the pan are not form-fitting in all directions are connected to each other and therefore when the tool and the workpiece spindle can fall apart. This applies in particular to all Cases where the ball pin is attached to the upper spindle. Since he's only Compressive forces and no tensile forces can be transmitted, the associated fall Components due to their weight down when the spindles apart will drive. If the ball pin is located on the lower spindle and a Therefore, do not fall apart, there are other problems with The spindles move apart, as they are connected to the ball pin Components (pan with mold or lens holder) in any direction can tilt. This is related to the gimbal flexibility the combination ball pin / pan. In both cases (falling apart or Inclines), automatic loading of the machine is not possible, d. H. With the traditional ball pen method, manual intervention is always required.
• - Since the combination ball pin / socket functions as a bearing with a freewheel kung, no rotational movements from the related Spindle on the connected mold or alternatively connected be transferred to its lens holder. The transmission of such rotary movements but would be very desirable, since this corrects the corrections mentioned on the Have the lens geometry carried out in the fine area.

The further prior art results, for. B. from a Japanese patent with the publication number: JP 7164297, the publication date 27-06-95 and the Application number JP 930341759, which is also filed with the European Patent Office was enough.  

A combined tool is called "Grinding Method And Device" described, in which a pot tool is connected to a mold. The molding tool is arranged in the interior of the pot tool and is guided by an axially displaceable ball pin.

This combined tool has the advantage that the com combination pot tool / forming tool with a single tool spindle other two operations can be carried out, however A traditional ball pin is used, this combination results ten tools all the disadvantages, as previously related to the ball pen procedures have already been described.

So z. B. the combined tool and the lens holder to their positions change the machine spindles if a concave / convex lens is being machined it should, since here too the ball pin is only connected to the concave component may be. Other disadvantages are that the tool size is limited is, only low speeds are possible and a sensitive work together slope with the adjustment drive of the ball pin is not possible. There is also a ho forth wear between ball and pan and the problems mentioned in the au automatic loading with this combined tool the state of the art, is not possible. In particular, however, is a targeted drive of the mold via the tool spindle is not possible because the ball pin with his pan has a free-running function. Targeted corrections to the lens geome trie through different relative speeds between lens and molding Stuff are therefore not possible.

The disadvantages mentioned, which are in the lens production according to the state of the art Technology and especially in connection with the combined tool ent speaking of the Japanese publication mentioned, with the here proposed combination tool for processing optical lenses avoided.  

The combination tool according to the invention takes advantage of the ball pen method while avoiding its disadvantages. Added to this is the particularly advantageous one Possibility of targeting the molding tool to correct the lens geometry to drive.

The structure of the combination tool is as follows:
It has a central body, which is detachably connected to the machine tool spindle. The tool spindle is in turn connected to a drive with which it can be set in rotation. The tool spindle can be tilted by means of a swivel head or can be moved linearly using corresponding linear guides (e.g. X-axis and / or Z-axis): There are also versions in which the movements mentioned are not, or in some cases, not , are carried out by the tool spindle but by the workpiece spindle arranged opposite it. The machine preferably has a CNC control. The possible uses of the combination tool are not restricted by the different structure of the various processing machines.

A pot tool is detachably attached to the central body of the combination tool, which has a ring edge on its open side, usually with diaman is equipped and is used for rough or fine grinding of the lenses. Inside, cylindrical cavity of the pot tool is housed a mold that can perform axial movements relative to the pot tool. If that's shape tool has moved forward, it protrudes over the ring lip of the pot mechanism stuff and can be brought into contact with the lens to be processed. Depending on whether the molding tool is coated with grinding pellets or polishing film, then fine grinding or polishing operations can be carried out with it. These operations with the molding tool follow on from the previous ones operations with the pot tool.  

So that the molding tool can be attached to the lens to be machined without constraint gen, it is stored in the combination tool so that it with respect to its Win cello is freely movable, similar to the known ball pen method is the case, but without having to accept the disadvantages.

For this purpose, it is preferably supported in the radial direction with its spherical peripheral surface point against the inner cylindrical wall of the cavity in the pot tool. However, versions are also provided in which the molding tool with its spherical peripheral surface against the inner peripheral surface of another Component is supported.

The spherical design of this circumferential surface allows the molding tool to look like this move as if held by a ball pin; d. H. with this "gimbal" Storage ensures that the mold is not in the radial direction can move, but swivel movements are possible. This swivel movement conditions lead to the fact that the symmetry axis of the molding tool in the predetermined Angular range can take any desired angular positions and the mold aligns itself with the lens without force. This results in significantly better lens qualities, especially in terms of shape accuracy, than if the mold were rigidly connected to the tool spindle, like this is common in the prior art.

Because of the robust guidance of the mold on its spherical circumferential surface there are also no restrictions regarding its curvature (concave and convex) and in terms of its size and speed. Such restrictions give up however in the ball pen method.  

A vacuum can be applied to the back of the mold sufficiently large holding forces that prevent the mold from falling out prevent the potting tool when z. B. the combination tool and the finished bear processed lens can be moved apart.

The mold is also in its front end position by one or held several stops, which are arranged so that the mold can move axially by the specified path. With one of several possible The stops are designed as stop disks, which are designed by Guide bolts are held. The game between the Dimension the mold and the guide pin so that the above Swiveling movements are not hindered. If the vacuum is caused by a Machine fail, the mold is still from that Stop or the stops held securely. This is another disadvantage of the known ball pen method avoided, which is that Shaping tool in the axial direction from the ball pin against falling out is held.

Machines that are equipped with the combination tool according to the invention can because of the secure hold of the mold without restriction with an auto matical feed are operated. Because the mold is in operation aligns with other components in a stable position with respect to the Tool spindle also a clearly defined position, which also gave way is a prerequisite for automatic loading processes. This clearly de Naturally, there is no defined position in the ball pen method.

So alternatively and in succession with the pot tool or with the molding Stuff can be worked, it is provided that the molding tool both one Execute driven forward stroke as well as a driven reverse stroke can.  

After processing the lens with the pot tool, the mold comes for use. For this purpose, the mold is adjusted as far as possible with the forward stroke pushed in front that it protrudes beyond the pot tool and in contact with the Lens is coming. Then the machining can be carried out with the molding tool be performed.

With the backward stroke, the molding tool then gets this far again moved back that the ring cutting edge of the pot tool in contact with the next lens can be brought without causing collisions with the Molding tool is coming. The possibility of two is a particular advantage Carry out operations with only one tool and one tool spindle.

A diaphragm, which is located on the back of the Molding tool (facing the spindle) and on their own back can be pressurized. For this purpose, the tool spindle and the Central body flow channels in the form of axial bores. As a result of Overpressure, the membrane bulges in the direction of the mold and lies against it ses on. In doing so, she pushes the molding tool out of the pot the required way tool out. An overstretching of the membrane is indicated by the above prevents impact if there is no contact between the molding unit during the forward stroke stuff and the lens takes place.

As mentioned, the stops are preferably used as stop disks in the area carried out by guide bolts. By using a membrane is prevented that the z. B. applied by air on the back of the mold Overpressure for a constant blowing through of the pressure medium at the gap between rule the spherical peripheral surface of the mold and the inner cylindrical Wall of the potting tool leads.  

The soft and elastic membrane also has the advantage that the Winkelbe Mobility of the mold when aligning its axis with the axis of the Lens is in no way obstructed when the two components touch. The Forces exerted by the membrane on the mold have the same effect moderate and flat and only in the desired direction, without the harmful Tipping moments arise.

The reverse stroke can, in one of several provided versions of Compression springs are driven, the one hand against the mold and on the other hand supported against construction elements, which are preferably with the Pot tool or the central body are connected. With this construction elements can preferably be the stop disks, which in the loading are richly arranged by guide bolts. The compression springs are when moving forward stroke stretched by the force of the membrane and ent during the reverse stroke tensions when the diaphragm is relieved of pressure to initiate the reverse stroke. If such compression springs are provided, their spring travel is dimensioned that they can absorb the full forward stroke generated by the membrane.

In another embodiment it is provided that the reverse stroke by means of sub pressure is driven to the back of the membrane via the above Flow channels in the tool spindle and the central body is created. For The membrane is equipped with a check valve for the reverse stroke when applying vacuum opens so that it also on the back of the mold tool can work and this moves. When applying overpressure to the Membrane back closes the check valve again, so that the membrane with the mold can perform the forward stroke without the pressure medium escapes.  

Since the reverse stroke in this embodiment is indicated by the negative pressure to be driven, the membrane must be out with the check valve mentioned be prepared. This is the only way to ensure that the negative pressure on the back of the Mold works permanently, even if air flows in through leaks. The between the mold and the membrane, due to their backward movement Short-term negative pressure is quickly reduced by the leakages mentioned built so that the negative pressure only by sucking off the leak air with means the check valve and the flow channels in the tool spindle and the central body can be maintained.

Since the membrane only press against the mold, but not pull on it a pressure-controlled reverse stroke would not be possible without a check valve.

This means that there is not always air during the reverse stroke due to the negative pressure applied due to the leakage in the spherical peripheral surface of the mold and the non-return valve flows, the membrane at its front wipes off one Sealing lip. At the end of the reverse stroke, the molding tool lies down with its Back against this sealing lip, so that there is a tight seal and none Air can flow in more. At the same time, this sealing lip forms a soft touch beat, so that the mold is gently braked during the reverse stroke and occupies a clearly defined position. The exact location of the mold is for automatic operation with mechanical loading is particularly important.

There are also versions of the combination tool in which the rear upward stroke due to the combined force of the springs and the vacuum on the Back of the mold is driven.  

By using an elastic membrane with valve to drive the front upward and backward stroke, the movements of the molding tool advantageously perform very delicately. This is related to the minor Mass of the membrane and the lack of frictional forces on this membrane as Drive element. In contrast, the air cylinders are how they move be used by ball pins, with larger masses and above all undesirable tears occur on the piston seals and the axial guides exercise staff, which makes sensitive work impossible. With the fiction According to the combination tool, these disadvantages of the known ball pen method completely avoided, as a diaphragm with their own in the tool for the drive advantageous properties is arranged and thus air cylinders can be avoided can.

So that negative pressure or positive pressure are applied to the back of the membrane can, both the central body and the tool spindle are with the named central axial bores. The preferred printing medium is Compressed air is used to supply the tool spindle with suitable rotary unions is directed. These rotary unions are because of the rotation of the factory tool spindle required.

Since the membrane for attachment between the central body and preferably the potting tool is firmly clamped, torques can also be used with it and thus drive energy from the spindle to the mold via the central body tool can be transferred. When the membrane is pressurized and has applied itself to the molding tool, the frictional forces between are sufficient between the two components around the drive required for machining to transmit torques. The guide bolts provided for one version zen should not transmit this drive torque according to the invention, so that free movement of the mold is retained.  

By transferring drive energy from the tool spindle to the mold tool, the corrections to the lens geometry already mentioned in the Make fine range. The speeds of the tool spindle and the workpiece spindle matched so that the relative movements between tool and lens depending on the lens radius the desired Have course. The following applies: the greater the relative movement, the larger the mate rial removal and vice versa.

The advantageous properties of the membrane are also evident here. The To The drive torque is soft and transmits every constraint. Come in addition damping harmful torsional vibrations.

The above-mentioned possibility of targeted correction by selecting the spindle speeds Reaching the lens geometry is a significant advantage for the inventor combination tool according to the invention.

In the known ball pen method, such corrections are not possible because in Torque / socket area no torques can be transmitted. To that extent is the targeted, rotary drive of the "cardanic" mold one of the important features of the invention.

It is also advantageous that none within the combination tool according to the invention rotational relative movements take place, as is the case in the prior art between the ball pin and pan is the case where the pan is around the fixed standing ball rotates. This creates friction and wear. The rotation at Ball pin method is triggered by the friction between the driven Lens and the attached mold. In contrast to this, the front struck combination tool the mold over the intermediate Membrane and other components against rotation with the driven work tool spindle connected. Wear due to rotary relative movements takes place therefore not instead.  

Another advantage of the combination tool according to the invention is that the associated mold both convex and concave work surface Chen can have. The guide of the mold with its large, crowned Circumferential surface in the pot tool is extremely stable. Here can be essential Lich greater forces are transmitted than with the ball pen method with the relatively small combination ball / pan is possible. As mentioned above Ball pin always only fixes components (lenses / tools) with concave curvature be otherwise the reaction forces during processing become too great and the Jump components apart. A change from the tool to the lens Holder is therefore not necessary in the combination tool according to the invention, too if the curvature of the tool is convex. Because of the stable structure of the Combination tools are also no restrictions on diameter ratio lens / mold to be observed.

Generally it can be said that the positive properties of the Combination tool according to the invention were also achieved, among other things, that the different functions of a ball pin with pan on multiple components were relocated and the ball pen itself, including its pan, with full preservation of all Functions that could be avoided. This naturally eliminates everyone Disadvantages associated with the ball pin. It is no longer there.

The various functions of a ball pin are guaranteed with the combination tool as follows without a ball pin being available:

• - The "cardanic" compensation for the angular mobility of the mold becomes generated from its spherical peripheral surface, d. H. directly from the component where the reaction forces occur during machining. Accordingly it can be used with little vibration.
• - For the generation of the working pressure, the forces required are flat transfer a membrane to the mold.  
• - This results in very even pressure ratios between Mold and lens and also good damping of vibrations, which has a positive effect on the work result.
• - The relative position of the mold and lens to each other is fixed about the circumference of the mold and the membrane. This results in very stable and low-vibration conditions.
• - A bearing for rotary relative movements is not necessary because the rotation Movement of the mold is driven by the tool spindle, the is accordingly well stored. Wear caused by bearing friction in the combination plant Stuff is therefore completely eliminated.

In the ball pen method, the four tasks mentioned must be performed by the Kombina tion ball / pan are taken over, which due to the high stress ser two components leads to the problems mentioned above. As a special one additional advantage that not ge in all known ball pen method is given, results in connection with the combination plant according to the invention testifies to the possibility of making corrections in the fine range on the lens geometry men. As mentioned, this is made possible by means of the driven molding tool.

Further advantages of the combination tool according to the invention are the following:

• - The operation and programming of the processing machines is relatively one fold, since only the movements of an upper and a lower spindle program must be lubricated. When using conventional tools, would have to In contrast, three spindles programmed to achieve the same work result become.  
• - The moving together of the mold and lens is not critical, because paths in the Fine range, d. H. shortly before the two components meet, from the mem bridges can be bridged. This can reduce the machine running times be adjusted because the safety distances can be chosen smaller (it finds less "air cutting" instead). The "gimbal" suspension of the mold also has a positive effect in this context, since the work witness, with regard to its angular position, automatically adapts to the lens in the fine range.
• - Simpler machines, i. H. Machines with only one upper and one lower Spindle, can be used because the combination tool allows two working gears enabled. If using conventional tools would be here required for a total of three spindles. From the use of simpler machines result in lower investment and operating costs. At the one after the other The pot always comes first during the current work steps of the combination tool tool and then the molding tool.

These operations can be rough and fine grinding, the Fine grinding and polishing or pre-and finish polishing; d. That is, the combination tool can be used very universally, which is in practice brings many advantages.

• - Because of its stable structure and vibration-damping behavior can the combination tool according to the invention also on fast-running, moder CNC-controlled machines can be used. This leaves together saw a further increase in profitability with his pot tool, because the cutting performance is roughly proportional to the cutting speed.
• - With the mold of the combination tool according to the invention can be produce much better qualities than with the usual pot tools, at which the quality produced depends very much on the accuracy of the machine and ih control depends.

This applies both to the roughness and to the geometry created (Shape accuracy) of the lenses produced. When it comes to shape accuracy Dimensional deviations achieved according to the invention at 0.1 to 0.2 microns instead of otherwise, according to the prior art usual 1 to 2 microns, d. H. the shape accuracy is 10 times better than usual.

This is achieved through the use of the high-precision mold, which without every tilt is brought into contact with the lens and due to its stable Storage and especially the damping effect of the membrane vibrations coming from the spindle, compensated. In this context, a subdued procedure. With the molding tool, he becomes generation of the optimal accuracy, always the last of the two with the Combination tool possible operations performed.

• - A further increase in lens quality results from the small incisions speeds that can be achieved with the molding tool. Applied cutting speeds between 0.2 and 0.5 m / sec. instead of with other tools usual cutting speeds of 20 to 40 mfsec. These low cutting speeds reduce the speed again problems and reduce the risk of deep cracking. When lows Crack formation occurs, these errors must be elaborate and thus expensive any polishing processes can be eliminated.
• - When working with molding tools, an effect occurs that is called aquaplaning is drawn and allows a much finer grinding than this with a pot tools e.g. B. is possible. Aquaplaning creates a thin what serfilm between the surface of the tool and the lens. This water film has a vibration-dampening effect on the components involved and leads to a small one The grinding wheels (e.g. diamond) engage the surface of the lens. The so The roughness achieved is two to three times better than with conventional fine grinding with potted tools.  
• - The economy can also be reduced when using the combination tool increase at least a factor of 2. This is due to the fact that with the Combination tool two operations can be carried out in succession, without a tool change or a change of the work spindles or the Machine would be required. In particular, this has in the combination tool integrated molding tool a very high material removal rate in the ver for processing the lenses with a potting tool. This higher abtra performance results with the molding tool despite the smaller cut and is due to the flat contact of his pellets with the lenses surface attributed. On the other hand, there is only one line in the pot tool touch instead. Due to the flat contact, more grinding tools (e.g. slide shell grains) in use, which results in the greater cutting performance.

In order that these advantageous properties can be achieved, the combination tool according to the invention has a number of special design features, which are explained below using an example and Figs. 1 to 3.

However, other versions are also provided, in particular individual functions can be taken over by other components. These others Components can then also be arranged differently.

Fig. 1 shows the combination tool with a vertical axis and attached to a tool spindle.

Fig. 2 shows the combination tool with an inclined axis when machining a lens with the pot tool.

Fig. 3 shows the combination tool with an inclined axis when machining a lens with the molding tool.

To Fig. 1

Based on this illustration, the basic structure of the combination tool is explained. The central body ( 1 ) is detachably fastened to the tool spindle ( 3 ) of a processing machine by means of a receiving device ( 2 ). The tool spindle ( 3 ) is connected to the spindle guide ( 5 ) by means of the bearing ( 4 ).

The pot tool ( 6 ) is fastened to the underside of the central body ( 1 ) by means of the screws ( 7 ). The pot tool ( 6 ) has an annular cutting edge ( 8 ) on its lower open edge, which is set with diamond grains. With the pot tool ( 6 ) guide bolts ( 9 ) are connected, which are held by screws ( 10 ). These guide bolts ( 9 ) protrude into bores ( 11 ) of the molding tool ( 12 ). The molding tool ( 12 ) is accommodated in the cylindrical, inner cavity ( 29 ) of the pot tool ( 6 ). The guide bolts ( 9 ) carry stop disks ( 13 ) at their lower end.

In the bores ( 11 ) and concentric to the guide bolts ( 9 ) Druckfe countries ( 14 ) are arranged, each with its lower end against the stop disc ( 13 ) and with its upper end against a shoulder ( 15 ) in the Boh Support ( 11 ). The stop discs ( 13 ) are held on the guide bolts ( 9 ) by means of the screws ( 16 ). The molding tool ( 12 ) has a spherical peripheral surface ( 17 ) on its outer circumference and is equipped with grinding pellets ( 18 ) on its underside. Depending on the intended use, the molding tool ( 12 ) can also be coated with polishing film instead of grinding pellets ( 18 ).

The spherical peripheral surface ( 17 ) guides the molding tool ( 12 ) very precisely in the radial direction, while it is displaceable in the axial direction. At the same time, the spherical peripheral surface ( 17 ) ensures the full angular mobility of the molding tool ( 12 ) in a predetermined angular range.

A membrane ( 19 ) is arranged between the central body ( 1 ) and the molding tool ( 12 ), which is positively connected to the central body ( 1 ) and has a collar ( 20 ) for this purpose, which is inserted into a groove ( 21 ) in the central body ( 1 ) intervenes. In addition, the membrane ( 19 ) is still held by the inner circumference ( 22 ) of the pot tool ( 6 ), which reaches over it and prevents the bund ( 20 ) from jumping out of the groove ( 21 ). Due to the stable fastening of the membrane ( 19 ), it is also able to transmit torques from the central body ( 1 ) to the molding tool ( 12 ).

On its underside and in the area of its largest diameter, the membrane ( 19 ) has a sealing lip ( 23 ), while a non-return valve ( 24 ) is provided on its top. Both the sealing lip ( 23 ) and the check valve ( 24 ) and the collar ( 20 ) consist of the same material as the membrane ( 19 ) and are generated in the manufacturing process, so that the four construction parts form a unit.

The sealing lip ( 23 ) has the function of a seal against the molding tool ( 12 ) and serves this as a stop at the end of the reverse stroke. The check valve ( 24 ) also has two functions. It is a flow channel when operating with negative pressure, while it forms a closure when operating with positive pressure.

The back ( 25 ) of the molding tool ( 12 ) has a concave, spherical shape and receives the membrane when subjected to excess pressure. In contrast, the back ( 25 ) bears against the sealing lip ( 23 ) of the membrane ( 19 ) when the back side ( 25 ) is pressurized. The back ( 25 ) and the sealing lip ( 23 ) then form a gas-tight seal. The bore ( 27 ) in the Zen tralkkörper ( 1 ) is dimensioned so that it can accommodate the check valve ( 24 ) when operating with negative pressure.

This negative pressure is applied via a central bore ( 26 ) which is arranged in the tool spindle ( 3 ) and a bore ( 27 ) which is arranged in the central body ( 1 ) at the rear of the membrane ( 19 ). Under the influence of the negative pressure, the check valve ( 24 ) opens so that it can also act on the rear ( 25 ) of the molding tool ( 12 ). This leads to the backward stroke of the molding tool ( 12 ), which is supported by the compression springs ( 14 ).

If an overpressure is applied to the membrane ( 19 ) via the bore ( 26 ) and the bore ( 27 ) instead of negative pressure, the check valve ( 24 ) closes and the membrane ( 19 ) bulges downwards. It comes into contact with the back ( 25 ) of the mold ( 12 ) and pushes it down (forward stroke). The compression springs ( 14 ) are tensioned during the forward stroke. The stop disks ( 13 ) prevent the membrane ( 19 ) from overstretching if the mold ( 12 ) does not come into contact with the lens ( 28 ) during the forward stroke due to incorrect control.

The free angular mobility of the mold ( 12 ) is ensured by its spherical circumferential surface ( 17 ). The play between the guide pin ( 9 ) on the one hand and the bores ( 11 ) with the shoulder ( 15 ) on the other hand is dimensioned so that this angular mobility is not hindered.

To Fig. 2

This figure shows the combination tool with an inclined axis when machining a lens ( 28 ) with the pot tool ( 6 ). For this purpose, the combi tool is attached to an inclined tool spindle ( 3 ) which rotates in the same direction as the lens ( 28 ). The tool spindle ( 3 ) can be brought into the said inclined position by means of a swivel head (not shown) which is part of the processing machine.

The membrane ( 19 ) is pressurized via the bore ( 26 ) and the bore ( 27 ), whereby the check valve ( 24 ) opens and the molding tool ( 12 ) at the end of the reverse stroke against the sealing lip ( 23 ) of the membrane ( 19 ) was sucked.

Due to the negative pressure and the action of the compression springs ( 14 ), the molding tool ( 12 ) is securely held in its rear position, so that the lens ( 28 ) can be processed with the pot tool ( 6 ) without causing collisions with the Molding tool ( 12 ) comes.

The interaction of the sealing lip ( 23 ) and the back ( 25 ) of the molding tool ( 12 ) seals the space between the membrane ( 19 ) and the molding tool ( 12 ) to the atmosphere, so that no leakage air through the play between the spherical peripheral surface ( 17 ) and the cylindrical wall of the inner cavity ( 29 ) can penetrate. The inflow of leakage air would be particularly harmful because it would also suck in cooling liquid.

The grinding process then runs with the addition of cooling liquid with the pot tool ( 6 ) on the lens ( 28 ), the radius of curvature of the generated Lin surface resulting from the inclination of the tool. The axes of the tool spindle ( 3 ) and thus also of the pot tool ( 6 ) intersect with the axis of the lens ( 28 ) in the center of curvature of the lens ( 28 ) generated.

To Fig. 3

This figure shows the combination tool when processing a lens ( 28 ) with the molding tool ( 12 ). For this purpose, the combination tool is again attached to the tool spindle ( 3 ) which is inclined by means of a swivel head and which rotates in the same direction as the lens ( 28 ).

The angle of the inclination was chosen so that the centers of curvature of the mold ( 12 ) and the lens ( 28 ) coincide in the axis intersection of the tool spindle ( 3 ) and lens ( 28 ).

In this case, the membrane ( 19 ) is pressurized via the bore ( 26 ) and the bore ( 27 ), as a result of which the check valve ( 24 ) has been closed and the molding tool ( 12 ) has carried out the forward stroke. For this purpose, the membrane ( 19 ) has placed on the back ( 25 ) of the molding tool ( 12 ) and pressed it forward under the influence of the excess pressure. Since the Rückschlagven valve ( 24 ) has closed, no leakage air can escape from the gap between the spherical peripheral surface ( 17 ) and the cylindrical peripheral surface of the inner cylindrical cavity ( 29 ). The compression springs ( 14 ) were tensioned during the forward stroke. The forward stroke is limited by the fact that the molding tool ( 12 ) with its grinding pellets ( 18 ) has placed itself on the surface of the lens ( 28 ).

Due to the overpressure, the molding tool ( 12 ) with its grinding pellets ( 18 ) is pressed securely against the surface of the lens ( 28 ) to be machined. During the machining process, the excess pressure is maintained and the required working pressure is brought between the grinding pellets ( 18 ) and the surface of the lens ( 28 ). The fine grinding of the lens ( 28 ) then runs with the addition of coolant.

Instead of grinding pellets ( 18 ), of course, polishing film can also be attached to the molding tool ( 12 ). The possible polishing processes are then carried out with the addition of polishing suspension.

To improve the work result, the overpressure during the processing of the lens ( 28 ) can also be varied with the molding tool ( 12 ).

So z. B. provided to reduce the excess pressure towards the end of the processing of a lens ( 28 ), as a result of which the roughness depth generated can be reduced again and thus improved.

The geometric dimensions of the combination tool and the settings of the machine axes were chosen so that there are no collisions with the pot tool ( 6 ). Such collisions must be avoided under all circumstances so that the components involved are not damaged. Since the coarser work steps are carried out with the pot tool ( 6 ), this tool must no longer touch the finely machined lens ( 28 ) at the end of the work.

Reference list

1

Central body

2nd

Cradle

3rd

Tool spindle

4th

camp

5

Spindle guide

6

Potting tool

7

screw

8th

Ring edge

9

Guide pin

10th

screw

11

drilling

12th

Molding tool

13

Stop disc

14

Compression spring

15

paragraph

16

screw

17th

spherical circumferential surface

18th

Grinding pellet

19th

membrane

20th

Federation

21

Groove

22

inner scope

23

Sealing lip

24th

check valve

25th

Back of the mold

26

drilling

27

drilling

28

lens

29

inner cavity

Claims (15)

1. Combination tool for processing optical lenses with two coaxially arranged tools, which are a pot tool and a molding tool, the molding tool being arranged axially displaceably in the interior of the combination tool so that its storage has a certain angular movement with respect to its axis of symmetry allows, characterized ,
that the combination tool is releasably connected to a driven tool spindle ( 3 ) which rotates in the same direction as the lens ( 28 ) and
that the mold ( 12 ) has an outer, spherical peripheral surface ( 17 ) which is connected to an inner cylindrical peripheral surface in the cavity of the combination tool, with little bearing play, and
that between the underside of the central body ( 1 ) and the back ( 25 ) of the mold ( 12 ) there is an elastic membrane ( 19 ) which is firmly connected to the central body ( 1 ) and
that the back of the membrane ( 19 ) with an axial bore ( 27 ) in the central body ( 1 ) and this in turn with an axial bore ( 26 ) in the tool spindle ( 3 ) and
that the bore ( 26 ) is connected to a rotary feedthrough and other equipment of the processing machine with which the bore ( 26 ) can be subjected to negative or positive pressure and
that facilities are available that allow the backward stroke of the mold ( 12 ) and
that there is at least one stop which limits the forward stroke of the molding tool ( 12 ). 2. Combination tool according to claim 1, characterized in that the spherical peripheral surface ( 17 ) of the mold ( 12 ) with the cylindrical peripheral surface of the inner cavity ( 29 ) is in communication, which is present in the pot tool ( 6 ). 3. Combination tool according to claim 1 and 2, characterized in that the membrane ( 19 ) has a check valve ( 24 ) on its back, which is pressurized with positive or negative pressure, which opens at negative pressure and closes at positive pressure. 4. Combination tool according to claim 1 to 3, characterized in that the bore ( 27 ) of the central body ( 1 ) is dimensioned with respect to its diameter and length so that the check valve ( 24 ) finds its place. 5. Combination tool according to claim 1 to 4, characterized in that the membrane ( 19 ) by means of a collar ( 20 ) in a groove ( 21 ) of the central body ( 1 ) is held positively. 6. Combination tool according to claim 1 to 5, characterized in that the pot tool ( 6 ) with its inner periphery ( 22 ) comprises the membrane ( 19 ) in Teilbe rich. 7. Combination tool according to claim 1 to 6, characterized in that a sealing lip ( 23 ) is provided on the underside of the membrane ( 19 ). 8. Combination tool according to claim 1 to 7, characterized in that the membrane ( 19 ), the check valve ( 24 ), the collar ( 20 ) and the sealing lip ( 23 ) consist of the same elastic material and are connected to one another without separating surfaces. 9. Combination tool according to claim 1 to 8, characterized in that the combination tool by means of its central body ( 1 ) is detachably connected to the tool spindle del ( 3 ), for which purpose a receiving device ( 2 ) on the tool spindle del ( 3 ) is present. 10. Combination tool according to claim 1 to 9, characterized in that the pot tool ( 6 ) is detachably connected to the central body ( 1 ). 11. Combination tool according to claim 1 to 10, characterized in that the stops for limiting the stroke of the molding tool ( 12 ) as a stop disc ben ( 13 ) are formed, which are located at the lower end of guide bolts ( 9 ), which in turn with the pot tool ( 6 ) stay in contact. 12. Combination tool according to claim 1 to 11, characterized in that there is enough play between the guide pin ( 9 ) and the bores ( 11 ) in the mold ( 12 ) to ensure the angular mobility of the mold ( 12 ). 13. Combination tool according to claim 1 to 12, characterized in that in the bores ( 11 ) of the mold ( 12 ) compression springs ( 14 ) are arranged which surround the guide bolts ( 9 ) and on the one hand against the stop discs ( 13 ) and on the other hand against Support paragraphs ( 15 ). 14. Combination tool according to claim 1 to 13, characterized in that the pot tool ( 6 ) has a diamond-coated ring cutter ( 8 ), the cross-sectional area of which has a rounded shape. 15. Combination tool according to claim 1 to 14, characterized in that the molding tool ( 12 ) is coated with grinding pellets ( 18 ) or alternatively with a polishing film.